西北非湿润区毛细阻滞覆盖层防渗性能验证与长期服役高危易渗气象段分析

Anti-seepage performance verification and analysis of high-risk permeable meteorological period of capillary barrier cover in Northwest non humid area

为研究西北非湿润区气候特征和毛细阻滞覆盖层高危易渗气象段,掌握该地自然气候条件下引发毛细阻滞覆盖层渗漏的气象机制,总结分析了西北干旱、半干旱气候区50年的降水、蒸腾蒸发和温度等气候特征。在西北某填埋场开展了毛细阻滞覆盖层足尺极端降水试验,验证了覆盖层在极端偶然降水事件下的防渗储水性能。耦合气候条件开展了土质覆盖层长期防渗性能分析,鉴别筛选出了西北干旱、半干旱气候区诱发渗漏的高危气象段,揭示了高危易渗气候段引发渗漏的气象机制。结果表明:(1)西北干旱、半干旱气候区4-11月降水多,12月-次年4月降水少,冬干夏湿,雨-热同期,利于土质覆盖层水分的存储-释放。(2)西北非湿润区极端偶然连续强降水量阈值在56.1~118.5 mm之间,现场覆盖层极端降水试验累计降水量194.85 mm,土层存储量148.22 mm。在该区极端偶然连续强降水条件下毛细阻滞覆盖层能满足防渗标准。(3)长期服役中西北干旱和半干旱气候区,8-11月是毛细阻滞覆盖层的高危易渗气象段,11-12月次之,1-7月渗漏可能最低。该气候区土质覆盖层防渗设计和填埋场运营-管理-维护工作中,8-11月为关键气象段,建议进行重点校核与管控。

Climatic characteristics of rainfall,transpiration,evaporation and temperature were summarized and analyzed in arid and semi-arid areas in the past 50 years.A full-scale extreme rainfall test of capillary barrier cover was carried out in a landfill in Northwest China to verify the impermeability with extreme rainfall accidents.Long-term anti-seepage performance of the cover was analyzed.The high-risk meteorological conditions of anti-seepage in arid and semi-arid areas were identified and screened.The meteorological mechanism of high-risk permeable meteorological period causing percolation was revealed.Results show that:(1)The precipitation in arid and semi-arid climate area of Northwest China is more from April to November,and less from December to April of the next year,with dry winter and wet summer.It is beneficial to the storage and release of water.(2)The threshold value of extreme accidental continuous heavy precipitation in the northwest non humid area is 56.1–118.5 mm.The cumulative rainfall of field cover extreme rainfall test is 194.85 mm,and the soil layer storage is 148.22 mm.With the condition of extreme accidental continuous heavy rainfall in this area,the capillary barrier cover can meet the anti-seepage standard.(3)In the arid and semi-arid climate region,August to November is the high-risk meteorological period for capillary barrier cover,followed by November to December.The possibility of percolation is the lowest from January to July.In the anti-seepage design of soil cover and the management of landfill,August to November can be regarded as a key meteorological period for verification and control.